This project is designed to define a possible association between virus infection and juvenile-type diabetes mellitus of recent onset. Patients at the Joslin Clinic (Boston) are identified and serum specimens are used in viral serologic studies. In addition, sera are obtained from siblings, playmates and other control subjects. The specimens are evaluated for antibodies against common viruses, particularly the coxsackieviruses and mumpsvirus using standard techniques. It is our plan to determine whether or not the incidence of persons with antibodies is greater in the diabetic group than appropriately matched controls. Charts of patients admitted to the Joslin Clinic from January 1, 1964 through December 31, 1974 are reviewed to ascertain demographic and medical information. Data is transposed to Termatrex cards and will be analyzed in the future in an effort to detect epidemiologic risk factors which may play a role in the etiology and pathogenesis of the disease.